Elevator-cable equalizer



Allg- 1929- D. L. LINDQUIST 1,725,402

ELEVATOR CABLE EQUALIZER Original Filed June 11, 1927 33M W INVEHTOI?F/af BY ATTORNEY Patented Aug. 20, 1929.

UNITED STATES DAVID L. LINDQUIST, OF HARTSDALE,

NEW YORK, ASSIGNOR TO COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEWOTIS ELEVATOR JERSEY.

\ ELEVATOR-CABLE EQUALIZER.

Application filed June 11, 1927, Serial No. 198,075.

This invention relates to equalizers for elevator hoisting ropes.

In traction elevator systems wherein solid hitches are employed forconnecting the hoisting ropes to the elevator car and its counterweight,these ropes may sustain unequal portions of the load. This inequality ofload distribution may be due to various factors, such as difference inthe diameters of the grooves of the driving sheave or un equalstretching of the ropes. lVhere such inequality exists, the ropescarrying the greater portion of rapid wear and possible breaking.

One feature of the invention is the provision of equalizers on both thecar and the counterweight ends of the hoisting ropes, which equalizerstend to maintain equal ten sion in all the ropes at any point.

Another feature of the invention is the provision of equalizers on boththe car and the counterweight ends of the hoisting ropes in which theequalizing members of each equalizer are biased to definite positionsrelative to each other.

A third feature is to provide equalizers of a construction that may bearranged for any number of hoisting ropes.

Still another feature resides in the provision of equalizers that are ofsimple construction, easily installed, and which occupy a minimum ofoverhead space.

Other features and advantages will become apparent from thespecification, taken in connection with the accompanying drawingswherein one embodiment of the invention is illustrated.

In the drawings Figure 1 is a schematic representation of an elevatorsystem illustrating the applica-' tion of hoisting; rope equalizers tothe elevator car and to the counterweight.

Figure 2 is an enlarged detail view taken along the line 22 of Figure 1.

Figure 3 is an enlarged detail view taken along the line 33 of Figure 1.

Figure is a diagrammatic representation of a portion of a hoisting ropeequalizer wherein four hoisting ropes are employed.

Referring to Figure 1, the hoisting motor 1 drives the sheave 2 foreffecting the raising and lowering of the elevator car 3 andcounterweight 4, three hoisting ropes 6 being shown for convenience ofdescription. An

theload are subjected to.

9 (see also Figure 1).

Renewed March 12, 1929.

electromagnetic brake 5 is a plied to the motor shaft for the purpose ofbringing the hoisting motor, and therefore the car and counterweight, toa stop.

According to the preferred arrangement, the ends of the hoisting ropes 6are secured to thimble rods 7 of hoisting rope equalizers 8 and 10.Equalizer 8 is secured to the car 3 and equalizer 10 is secured to thecounter-' weight4. Since hoisting rope equalizers 8 and 10 are of thesame construction, only one of these equalizers, namely equalizer 8,will be described.

As illustratedin Figure 2, equalizer 8 comprises a frame having a topplate 11 and a bottom plate 15, the bottom plate being connected to thecar! framework by clamps These plates are joined .by verticallyextending rods 14. These rods are secured to the top plate 11 as by nuts16 threaded on the rods and positioned on both sides of the plate.Similarly, these rods are secured to the bottomplate 15 as by nuts 17threaded on the rods and positioned on both sides of the plate. Thethimble rods 7 extend downwardly apertures provided in top plate 11 andare secured at their lower ends to sheave blocks 13, one for eachthimble rod. Each of these thimble rods is provided with a compressionspring 12, these springs surrounding their respective rods and extendingbetween the sheave blocks and the top plate. Each of the sheave blocksis flanged outwardly, these flanged portions being provided with bearingapertures through which rods 14 extend. By this arrangement, the sheaveblocks are restricted to vertical movement, the rods 14 serving asguides for the blocks.

Each of the sheave blocks is provided with depending arms 26 betweenwhich a sheave 25 is rotatably mounted. Two additional sheave blocks 21and 23 are pivotally secured to the bottom plate 15. Each of thesesheave blocks is provided with upwardly extending arms 27. A sheave 20is rotatably mounted between arms 27 of block 21 while a sheave through22 is rotatably mounted between the arms 27 of block 23. One end of 18is secured as by a hitch 19 to the bottom plate 15. From the hitch19,'the equalizer rope extends upwardly and around one of the sheaves25. From this sheave, rope 18 extends downwardly and around sheave 20.

an equalizer rope In a similar manner, rope 18 is 'led from sheave 2Oupwardly. and around another of sheaves 25, thence downwardly and aroundsheave 22 and thence upwardly and around the remaining sheave 25. Fromthis last sheave, rope 18is led downwardly to the bottom plate where itis secured as by a hitch 24. With such arrangement of the equalizerrope, sheaves 20 and 22 are positioned at an angle with respect tosheaves 25. Hitches 19 and 24: may be adjusted so as to lengthen orshorten the equalizer rope.

' Inasmuch as the'equalizer rope 18 extends around all of the sheaves25, the tension in the equalizer rope is equal at all points and eachsheave carries equal load.

In Figure 4: the equalizer is shown developed in a single plane in orderthat the manner in which the equalizer rope is extended around thevarious sheaves may be readily seen. In this figure, four hoisting ropesare illustrated, instead of three as in the other figures, todemonstrate that the equalizer may be arranged for other numbers ofhoisting ropes. It is believed that the operation of the system may bemore readily understood by reference to this figure. The

same reference characters will be employed,

namely, 6 for the hoisting ropes, 18 for the equalizer rope, 12 for thesprings, 25 for the V upper sheaves and 20 and 22 for two of the lowersheaves, the additional lower sheave being designated 28.

In order that the operation and advantages of the equalizer arrangementmay be readily understood, assume that only one of the movable bodies,for example the elevator car, is provided with an equalizer and that thesprings 12 are omitted. With such arrangement, although the' tension inthe hoisting ropes on the car side of the driving sheave is equalized,there is no equalization weight side of the sheave.

of the tension in-these ropes on the counter- For example, should thediameter of one of the grooves of the driving sheave be greater thanthat of the other grooves, during lifting of the counterweight, the roperunning in that groove is caused to bear the greatest portion of theload. The portion of the load carried by this rope increases as theupward movement of the counterweight continues until rope slippageoccurs at the driving sheave.

Assume now that both the car and the counterweight are provided withequalizers and that the springs 12 are omitted. Without the springs, theequalizers are in a state of unstable equilibrum. That is, no forcesexist tending to maintain the upper sheaves 25 in any particularrelative positions. With the car and counterweight at rest, the systemmay be adjusted so as to place the sheaves 25 of each equalizer in anydesired relative positions, for example in horizontal alignment asillustrated in Figure 4. So long as ency o would expand.

the car and counterweight remain at rest, these relative positions aremaintained, as the existingforces are balanced. When the car andcounterweight are started in operation, any resulting unbalance ,offorces, even though slight, causes relative movement of sheaves 25 toother positions, dependent on how the forces are unbalanced. Thisrelative shifting of the sheaves 25 of bothequalizers may continue untilthe limit of movement of one or more of the sheaves is reached in whichevent the equalizers are no longer capable of equalizing thetension inall the hoisting ropes. By way of specific example, assume that inoperation the left-hand hoisting rope of Figure 4 creeps on the drivingvented while the equalizers act at all times,

tending to equalize the-tension in thehoisting ropes. These springs tendto maintain the sheaves 25 of each equalizer in definite positions withrespect to each other. preferred to employ springs of the same size soas to tend to maintain the sheaves in horizontal alignment. Thesesprings are in effect biasing springs and may be rather weak.

In order that the action of the springs may be readily understood,assume that the car and the counterweight are at rest at equal distancesfrom the driving Isheave, that the hoisting ropes are of the same lengthand that the sheaves 25 of each equalizer are in horizontal alignment.Should there be a slight unbalance of forces when the system is inoperation such as is caused by a tendone of the hoisting ropes to creep,the springs act to prevent unrestrained shifting of the sheaves whichmight eventually result in all the clearance for the sheave 25 for thatrope being taken up and consequently the equalizers being renderedineffective. For example, should the left-hand hoisting rope 6 tend tocreep to the counterweight side of the driving sheave when the tis'system is in operation, spring 12 of the car equalizer for that ropewould be compressed while the other springs of the car equalizer Alsospring 12 of the counterweight equalizer for that rope would expandwhile the other springs of that equalizer would be compressed. Themovement of the sheaves in causing the differences of springcompressions also tends'to cause equalization of the tension in thehoisting 25 of both the car ropes. Thus,

hoisting ropes and sheaves '25 as before,

ropes act as bufi" a condition is reached where the unequal tensions ofthe hoisting ropes are balanced by the unequal spring compressions.Owing to the fact that the unbalance of forces due to rope creepage isrelatively small, this shifting of the sheaves and change of springcompression is very slight. Also, owing to the fact that the springs arerelatively weak, the change in rope tension is verysmall so thatsubstantially complete equalization is obtained.

With the assumption as regards relative car and counterweight relativepositions of assume now that the diameter of the groove in the drivingsheave,

for the left-hand rope 6 is larger than that of the others. Assumingthat the car is started in the up direction, during its upward movement,the left-hand rope 6 on the car side of the driving sheave tendsgradually to assume an increasing portion of the load. The equalizersact, however, to equalize the tension of the hoisting ropes, there beinga slight difference due to the inequality of spring compressionsresulting from the shifting of the sheaves 25. As previously pointedout, the springs 12 are relatively weak so'that the inequality of ropetensions is not very marked. Upon the reversal of car travel, theequalizers act oppositely so as to cause the sheaves 25 to resume theirhorizontal alignment upon the car and counterweight again beingequidistant from the driving sheave.

Should one of the hoisting ropes stretch, for example the left-hand rope6, springs 12 of both the car and the counterweight equalizers for thisrope expand equally to compensate for this change of length. Owing tothe fact that both the car and counterweight sheaves 25 for this ropemove downwardly, the remaining sheaves 25 move upwardly. In this manner,the tension in the hoisting ropes tends to become equal.

Should a hoisting rope'break, the sheaves and counterweight. equalizersfor the remaining hoisting ropes move upwardly, compressing theirsprings. Thus, the springs for the;.intact ers preventing any shockwhich might result from the engagement of the sheave blocks 13 with [topplate 11.

Should the equalizer rope of one of the.

respective eqpalizer act as buffers to eliminate the shockinertia instarting and sto ing.

As many changes could he, made in the above construction widelydifferent embodiments of this invention could be made the scope thereof,it is intended that all matter contained in the above description orshown in the accompanying drawings shall be interpreted as illustrativeand not in a limiting sense.

WVhat is claimed is:

positions, lengths of ,said elevator car; vdevlce connecting forequalizing the 'ing the car end of a counterweight; hoisting ropesextending from said car to said counterweight; an equalizing deviceconnecting said ropes to an additional equalizing said ropes tosaid-counterweight; and means associated with said equalizing devicesfor biasing the hoistin ropes to definite one another.

2.In an elevatorsystem; an'elevator can; a counterweight; hoisting ropesextending from said car to said coimterweight; means positions withrespect to for equalizing the tension in the hoisting ropes,

said means comprising a set tively movable equalizing member ofrelaconnecting the car end of the hoisting ropes to the car and anadditional set of relatively movable equalizing members connecting thecounterweight end ofgthe hoisting ropes to the counterweight; and meansfor biasingthe equalizing members of each set to certain definitepositions relative to each other.

3. In an elevator system; an elevator car; a counterweight; hoistingropes extending from said car to said counterweight; means forequalizing the tension in the hoisting ropes, said means comprising aset of relatively movable equalizing members connect ing the car end ofthe hoisting ropes to the car and an additional set of relativelymovable equalizing members connecting the counterweight end of thehoisting ropes to the counterweight the equalizing members of each setto horizontal alignment.

4. In an elevator system; an elevator car; a counterweight; hoistingropes extending from said car to said counterweight; means tension inthe hoisting ropes, said'means comprising a set of relatively movableequalizing members connectthe hoisting ropes to the car and anadditional set of relatively movable equalizing members connecting thetendency for the car to bounce due to itsand means for biasing I andmany apparently without departing from 1. In an elevator system; anelevator car;

counterweight end-of the hoisting ropes to a for equalizing the tensionin the. hoisting I hoisting ropes extending. said counterweight; meansropes, and means connecting the sheaves "of a the second set to thecounterwelght in such manner as to permit their relative movement; and aplurality of springs, one for each sheave of each set, for biasing thesheaves of each set to horizontal alignment.

6. In an elevator system; a movable body;

a hoisting ropes; equalizing means attaching said ropes to said movablebody and arranged to permit relative movement of said ropes;

and resilient means tending to restrain said relative movement.

.hoisting ropes comprising a plurality of d counterweight endsofthehoisting ropes in 7. In an elevator system; a movable body; v

hoisting ropes; a plurality of sheaves, each attached to a different oneof said hoisting ropes; a .plurality of additional sheaves attached tosaid movable body; roping led around said first and said additionalsheaves in alternation; and resilient means extending between saidfirstmentioned sheaves and said movable body.

8. A suspension device for connecting a movable body of an elevatorsystem to the hoisting ropes comprising; a plurality of sheaves, eachattached to a different one of said hoisting ropes; a plurality ofsh'eaves,

one less in number thansaid first mentioned sheaves, attached to saidmovable body; an equalizing rope secured at both ends to said movablebody and led around said first and second mentioned sheaves inalternation between its ends; and resilient means for biasing said firstmentioned sheavesto definite positions with respect to each other.

9. A suspension device for connecting a movable body of an elevatorsystem to the sheave blocks, one for each of said ropes anconnected'thereto; a plurality of sheaves, one for each sheave block,said sheaves being 'ournaled in their respective blocks; a plurality ofadditional sheaxze b1o cks, one less' in number than the first mentionedsheave blocks, said additional sheave blocks being pivotally connectedto said movable body; a plurality of additional sheaves, one for eachadditional sheave block, said additional sheaves being journaled intheir respective blocks; an equalizing rope anchored at both ends, saidrope being led around said first mentioned and additional sheaves inalternation between its ends; a member arranged above said firstmentioned sheave blocks and secured to said movable body; and aplurality of compression springs, one for each of said first mentionedsheave blocks,'s'aid springs extending between their respective sheave.blocks and said member.

between its ends around the sheaves connected to the car ends of thehoisting ropes and the sheaves carried by the car; springs tending tomaintain the sheaves connected to the car ends of the hoistin ropes indefinite positions relative to each 0t er; an additional sheave for eachhoisting rope and connected to the counterweight end thereof; sheavescarried by the counterweig t; roping connected at each end to thecounterweight and extending between its ends around the sheavesconnected to the counterweight ends of the hoisting ropes and thesheaves carried by the counterweight; and'springs tending to maintainthe sheaves connected to the definite positions relative to each other.

In testimony whereof, I have signed my 95:

name to this specification.

DAVID L. LINDQUIST.

